Surface characterization of Mo-implanted 6H-SiC by high temperature non-reactive wetting tests with the Ni-56Si alloy

The effects of Mo ion implantation into SiC monocrystalline substrates and succeeding annealing treatments on the interfacial characteristics of 6H-SiC were investigated by means of wettability tests. Ni (reactive) and the Ni-56Si alloy (non-reactive) have been used as liquid phases as a means to evidence the influence of surface and interfacial tensions on solid-liquid interactions. The variations of contact angle as a function of Mo implantation and of temperature are analyzed and discussed. The results indicated that a significant improvement of wettability was mainly related to the increase of surface energy ( ?SV) of SiC substrate and to the presence of Mo, rather than to the surface roughness of the ceramic substrate. With increasing annealing temperature, the contact angle of the Ni-56Si/SiC system increased as a result of the crystallization of the SiC amorphous surface and the loss of Mo at the substrate surface due to oxidation and diffusion/vaporization. The influence of these phenomena on technological processes such as metal-ceramic brazing is also taken into consideration.